Phagocytosis of particle-packaged drug molecules or antigen enables intracellular drug delivery, or inducing T-cell responses respectively. However, for particulate formulations within phagocytosable size ranges, phagocytes take up the particles and the encapsulated therapeutic agents largely become entrapped within the endosome and fail to reach their intracellular target. Thus, there is a need to overcome current problems in the art.